The present invention relates to a radiant wall, in particular for heat exchangers, muffle kilns and similar equipment.
Such a wall lends itself to use in numerous fields of application, and more especially, wherever there may be a requirement for treatment processes that involve an exchange of heat. A typical instance is that of a kiln, in which thermal energy produced by the combustion of solid or liquid fuels, or gas, is exploited for the purpose of firing materials such as ceramics, in particular, ceramic tiles.
Another possible application is that of the ordinary heat exchanger, by means of which thermal energy is transferred from one medium to another in order, for example, to effect a recovery of heat.
One particularly advantageous application of the invention is discernable in the firing of ceramic tiles, and more precisely, in kilns of the type by which thermal energy is transmitted to the ceramic material essentially by radiation.
Whilst the prior art does indeed embrace radiant burners, the results obtained from them have been less than satisfactory, as the amount of thermal energy effectively transmissible by radiation is limited. Moreover, a not inconsiderable amount of heat exchange will always take place by convection, as thermal energy is transferred to the material directly from the hot gases generated.
In the conventional muffle system, heat exchange by radiation from the kiln walls is made possible as a result of the thermal conduction properties of the material in which the walls themselves are embodied. Such a system tends to give low efficiency, however, and there are difficulties in maintaining a stable and geometrically exact configuration of the walls, especially if disposed flat and horizontal, in the face of stresses induced by high temperature levels; thus, it is not possible to make use of lightweight structures fashioned in materials possessing high thermal conductivity.
Accordingly, the object of the present invention is that of overcoming the drawbacks and shortcomings mentioned above.
Another object of the invention is to permit of embodying a radiant wall in materials with low heat conduction properties, which nonetheless can produce heat exchange coefficients of a high order, that is, equivalent to or even greater than those obtainable from walls giving nominally high thermal conduction.
An additional object of the invention is that of enabling adjustment of the flow of thermal energy through the wall, by way of a control facility that remains substantially independent of temperature conditions.